NASA mission to study snow in Ontario

This hamlet west of Lake Simcoe is where NASA sent its latest manned mission — scientists studying how snow falls.

The agency has a flying laboratory aboard a DC-8 aircraft, and has been flying joint missions with Environment Canada to fill gaps in our knowledge of how falling snow is measured.

Ordinary weather radar can show where snow is falling, and whether it’s a light flurry or major whiteout. But there are unknowns — for example, how much water is contained in that snow. That’s important to know in a world where fresh water is valuable and sometimes scarce.

Ordinary radar can’t tell dense, wet snow from powder.

As well, it can be tough to measure flakes that are blowing around as they fall. Rain comes down steadily. Snow can swirl around, blow sideways, and take its time falling.

NASA is building a satellite that measures snow and rain, called the Global Precipitation Measurement mission, to launch in 2014. But first it needs to test its equipment closer to Earth.

From mid-January until this week, the NASA scientists flew 13 times over southern Ontario, taking advantage of snow near the Great Lakes. Environment Canada also has an atmospheric research station in Egbert.

“Southern Ontario’s one of the best places because there’s such a variety” of snow types, said Joe Munchak of NASA’s Goddard Space Flight Institute.

A dry winter was worrying the scientists, until the day they woke up at their hotel in Barrie, Ont., and found 30 centimetres of snow on their cars.

The team took souvenir pictures. Normally their DC-8 is based in California.

“We were testing out some next-generation radar that will tell you about the size of flakes that are falling and something about the water content as well,” Munchak said.

“We got some really light snow, we got some lake-effect snow that was really good,” and finally conditions close to a blizzard late last week.

They also had days when snow and rain fell in a mix. “That’s going to be a really good source of data, because there’s a lot of scientific uncertainty” in trying to measure the rain-snow mix at a weather station. (Radar tends to interpret melting snowflakes as blizzard conditions.)

“Rain is easy,” he said. “It’s the variety in snow, the flake size and water content, that make it difficult to measure from a radar and satellite perspective.”

NASA’s radar can distinguish different sizes and shapes of different snowflakes, which are indicators of how much water a flake contains.

NASA also used a radiometer, which measures natural microwaves that come from the Earth all the time. Those waves interact with raindrops at a low frequency, and with snowflakes at a higher frequency. The radiometer can record this, and distinguish rain from snow.

The GPM satellite will have similar instruments.

While the NASA aircraft cruised above 30,000 feet, two smaller planes from the National Research Council and the University of North Dakota flew through the falling snow at lower altitude.